Internal-combustion engine



FIG. 1 is a left-front perspective view of an internal-combustion engine showing my new design;

FIG. 2 is a right-front perspective view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a front view thereof;

FIG. 6 is a rear view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom view thereof. 

The ornamental design for an internal-combustion engine, as shown and described. 